Radio tuning instrumentality



Sefit. 10, 1940. R DARDESS 2,214,659

RADIO TUNING INSTRUMENTALITY Filed Nov. 2. 1939 Patented Sept. 10, 1940 UNITED STATES PATENT orrlcs 4 Claims.

The present invention relates to improvements in radio tuning instrumentalities and more particularly to a condenser and volume control unit.

The primary object of the invention is to provide a tuning instrument for radio sets wherein two or more tuning devices are controlled by a single operating member to eliminate the manipulation of a series of control k'nobs or dials to obtain the correct tuning of the set being operated.

Another object of the invention is to provide a radio tuning device employing a variable condenser for controlling the resonance of the set in which a sliding shaft is provided for adjusting the condenser by rotary motion thereof and to provide a resistance element or volume control device operable upon sliding motion of the control shaft so that correct tuning may be established and the volume may be adjusted through the medium of single controlling element.

A still further object of this invention is to provide a radio tuning control unit of the above mentioned character having a unique slide connection between the condenser shaft and the rotor member of the condenser so that slippage will be prevented when the shaft is operating in a rotary manner but will allow sliding motion of the shaft axially with respect to the rotor member of the condenser during certain adjustments of the tuning unit.

Other objects and advantages of the invention will become apparent during the course of the following description of the accompanying drawing, wherein,

Figure 1 is a top elevational view of the control unit showing the pointer and graduated dial therefor;

Figure 2 is a vertical cross-sectional view of the control unit illustrating the tuning elements in their respective positions;

Figure 3 is a transverse cross-sectional View taken on a horizontal plane of Figure 2, showing the details of the operating shaft and the intermediate sleeve mounted thereon;

Figure 4 is a fragmentary side elevational view of the condenser rotor further illustrating the manner in which the intermediate sleeve is held in position.

Figure 5 is a fragmentary top elevational view showing the pointer for the control unit;

Figure 6 is an enlarged horizontal cross-sectional view showing the rotor sleeve and bearing member and the shape of the intermediate locking sleeve;

Figure '7 is a horizontal transverse sectional view taken on line l-'! of Figure 2; and

Figure 8 is an enlarged detail view of a fragment of the rheostat, showing portions of three collector rings wired to the resistance element 5 embedded in the di-electric cylinder of the rheostat.

In the drawing, wherein for the purpose of illustration, there is shown a preferred embodiment of the invention wherein like reference characters will be employed to designate like parts throughout the same, the reference numeral 5 will be employed to generally designate a casing cylindrical in shape, closed at one end by a bottom Wall 5 and provided at its opposite end with a closure 1.

Intermediate the ends of the cylindrical container 5 is a partition 8 providing an upper chamber 9 and a lower chamber it. Mounted in the upper chamber 9 is an insulation sleeve ll fitted against the wall of the cylindrical container 5 and embedded in the insulating sleeve H is a series of condenser stator plates i2 which are semi-circular and are cut away as at 53 in spaced relation from the rotor arbor M which has its opposite ends spun as at E5 and i6 providing bearing portions received in bearing openings IT and I8 respectively in the closure '5 and partition wall 8. An extension I9 is formed on the upper spun end l5 of the arbor i i and terminates in a pointer 20 adapted to cooperate with graduations 2| marked on the perimeter of the closure 1.

A series of condenser plates 22 is mounted on the arbor Hi and extend between the stator plates 12 as clearly shown in Figure 2, forming a conventional condenser structure as commonly used in radio tuning instrumentalities.

Mounted within the arbor M is a spring looking sleeve 23 having a lon itudinal split 24 and being elliptical in cross-section as shown clearly in Figure 6. Extending through the elliptical locking spring sleeve 23 is a control shaft 25 on one end of which is provided an operating knob 26 for effecting the rotary and sliding motion of the shaft 25. The shaft 25 urges the spring sleeve 23 outwardly into engagement with the cylindrical arbor i l, the sharpened edges 26 of the split spring sleeve 23 assisting in creating friction between the sleeve and arbor l4, while at the same time frictionally holding the operating rod 25 with respect to the cylindrical arbor I4 and condenser rotor plates 22.

The lowermost end of the operating rod 25 is provided with a socket 26 in which is positioned a plunger 21 held in place by means of a set screw 28 and said plunger 2'! is adapted to be moved downwardly to separate switch contacts 29 and 36 having foot portions 3| and 32 provided with binding posts or terminal screws 33 and 34 which may be connected in the supply circuit of the power unit so that the set may be turned on and oif upon sliding movement of the operating rod 25. The plunger 21 is formed of Bakelite or a condensation phenolic element so that the contact arms 29 and 30 will be separated to break the circuit in the power unit and it is to be noted that the upper ends 35 and 36 of the switch contacts are outwardly flared to allow the easy insertion of the plunger 2! without causing a snapping action or vibration likely to disrupt the movement of the tuning device from a set position.

Mounted on the intermediate partition plate 8 is a volume control unit 31 including a cylindrical member formed of a phenolic condensation product such as Bakelite and on one end or" the cylindrical insulating member there is provided an annular flange 38 capable of being fastened by screws 39 to the partition 8 so that the insulatin cylinder will depend therefrom and will be concentric with respect to the operating rod 35.

Embedded in the insulating cylinder 3'! is a resistance element 38 and at spaced intervals certain windings of the resistance element are connected to collector rings 4| mounted in the internal perimeter of the insulating cylinder 31. It is to be noted that the collector rings ii are not spiral but are arranged in horizontal spaced relation so that when engaged by a movable spring contact finger E2, the free end thereof as at 43 may wipe over the collector rings 4| without causing vibration or a threading action between the rings and the spring contact finger 42. The inner end of the spring contact finger 42 is connected to the lower end of the operating rod 25 by means of a set screw 24 whereby sliding mo tion of the operating rod 25 will cause the spring arm to wipe over the collector rings 4| and establish contact between certain areas of the resistance winding 48 in circuit with the grid elements of the amplifying tubes.

It is to be understood that rotation of the operating rod 25 will effect the tuning of the radio circuit by adjusting the rotor plates 22 with respect to the stator plates l2 and that sliding or reciprocating movement of the operating rod 25 will increase or decrease the resistance in the grid circuit by reason of the spring arm contact ill wiping over certain collector rings 4! and that after the volume has been controlled, other adjustments may be made to the condenser Without effecting the location of the spring arm 42. In normal operation, the rod 25, plunger 21 and spring arm l2 will assume the position shown in dotted lines in Figure 2 and as soon as the plunger 2'! is moved away from the contacts 29 and 3B, the circuit is closed in the radio set and the plunger spring element 42 may be adjusted with respect to the collector rings 4| to obtain the correct volume. In Figure 2, the full line position of the knob 26 indicates the extreme position of the volume control element wherein all of the resistance windings 40 will be in circuit with the grid elements.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred embodiment of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the sub-joined claims.

I claim:

1. A radio tuning device comprising a condenser including a stator and rotor, a control shaft extending through the rotor, a locking sleeve interposed between the control shaft and the rotor providing a non-slipping friction mounting for said shaft and a resistance element supported by the condenser and operable by the control shaft.

2. A radio receiver tuning device comprising a condenser having a stator and rotor, a cylindrical arbor for the rotor, an operating shaft extending through the arbor, a split spring sleeve interposed between the operating shaft and arbor and restrained from longitudinal movement relative to the arbor, and a control switch located on the end of the operating shaft.

3. A radio tuning device comprising a condenser having stator and rotor plates, an arbor for the rotor plates, an operating rod extending through the arbor, a split elliptic spring sleeve interposed between the arbor and operating shaft and interfittingly engaged with the arbor to be restrained from longitudinal movements relative to the arbor, a resistance element concentrically mounted with respect to the operating shaft, a spring finger mounted on the operating shaft and a control knob secured to the opposite end of the operating shaft.

4. A radio tuning device comprising a condenser having stator and rotor plates, an arbor for the rotor plates, an operating rod extending through the arbor, a split elliptic spring cylinder interposed between the arbor and operating shaft, a resistance element concentrically mounted with respect to the operating shaft, a spring finger mounted on the lower end of the operating shaft, an operating knob mounted on the upper end of the shaft, a switch contact located in axial alignment with the operating shaft and an insulating contact engaging member carried by the lower end of the operating shaft for engaging the switch contact.

RICHARD DARDESS. 

